The draft amendment to the constitution has not yet been forwarded for royal endorsement, cabinet secretary-general Ampon Kitti-ampon said yesterday.
Mr Ampon said the cabinet secretariat was still contacting the Office of His Majesty's Principal Private Secretary to obtain official permission to submit the draft for royal approval.
The draft seeking to amend the constitution's provisions governing the composition of the Senate was approved by a joint parliamentary sitting after its third reading on Saturday. Under the law, the prime minister has 20 days to submit the draft to His Majesty the King.
Prime Minister Yingluck Shinawatra signed her name on the draft on Tuesday. His Majesty will have 90 days to decide whether to endorse it. If the King does not grant his consent, both Houses can re-approve the draft to legalise it.
On Wednesday, the Constitution Court rejected a request for an injunction against the government's quest to seek royal approval for the draft amendment to the constitution.
In vetoing the request spearheaded by Somjate Boonthanom, the court ruled there were no reasons or time constraints to justify an injunction.
The Constitution Court explained its ruling corresponded with earlier decisions last week not to delay the third and final reading of the draft.
However, the court accepted for consideration petitions asking it to rule whether the amendment violated Section 68 of the constitution, which deals with acts that could undermine the constitutional monarchy or lead to the seizure of power via unconstitutional means.
The petitions were filed by Senator Somjate and Democrat Party MP for Songkhla Wirat Kalayasiri.
The amendment aims to change the system so all 200 senators will be elected rather than some appointed. It will also allow senators to run for consecutive terms which the present charter bans.
Prime Minister's Office secretary-general Suranand Vejjajiva yesterday said the charter court must act within the law. If the court eventually rules against the draft amendment, it must give Ms Yingluck "a way out", he said.
Mr Suranand said the prime minister is required by the charter to submit the draft for royal endorsement.
He added that there was no need for Ms Yingluck to resign or dissolve the House to show responsibility because she had not committed any wrongdoing in running the country.
Parliament President Somsak Kiatsuranont yesterday forwarded a separate petition filed against the draft amendment to the Constitution Court.
The petition was filed by the Group of 40 Senators, led by Rosana Tositrakul, and Democrat MPs.
Meanwhile, Suppawat Taksin, a lawyer representing the red-shirt United Front for Democracy against Dictatorship, yesterday filed a police complaint against the Group of 40 Senators.